Disk drive head gimbal assembly having a flexure tail with transverse flying leads
View Patent ↗A head gimbal assembly for a disk drive includes a read head, a load beam, and a laminate flexure. The laminate flexure includes a structural layer, a dielectric layer, and a conductive layer that includes a plurality of electrical traces. The laminate flexure includes a tongue portion that connects to the read head, and a flexure tail that extends away from the tongue portion and includes a plurality of flexure bond pads that may facilitate ultrasonic or ACF bonding. Each of the plurality of flexure bond pads consists of a widened region of a corresponding one of the plurality of electrical traces in the conductive layer, and a gold coating upon the widened region. The widened region of each of the plurality of electrical traces extends transverse to the flexure tail's longitudinal axis at least 2.5 times more than it extends parallel to the flexure tail's longitudinal axis.
1. A disk drive comprising:
a disk drive base;
a disk rotably mounted to the disk drive base;
an actuator rotably mounted to the disk drive base, the actuator including a flexible printed circuit (FPC) that includes a plurality of electrically conductive FPC bond pads; and
at least one head gimbal assembly attached to the actuator, the at least one head gimbal assembly comprising
a read head; and
a suspension assembly that comprises
a load beam, and
a laminate flexure that comprises a structural layer, a dielectric layer, and a conductive layer that includes a plurality of electrical traces, the laminate flexure including a tongue portion that connects to the read head and a flexure tail that extends to the plurality of FPC bond pads, the flexure tail defining a flexure tail longitudinal axis;
wherein the flexure tail includes a plurality of flexure bond pads, each of the plurality of flexure bond pads being aligned with a corresponding one of the plurality of FPC bond pads, each of the plurality of flexure bond pads consisting of
a widened region of a corresponding one of the plurality of electrical traces in the conductive layer, and
a gold coating upon the widened region;
wherein the widened region of each of the plurality of electrical traces extends transverse to the flexure tail longitudinal axis at least 2.5 times more than it extends parallel to the flexure tail longitudinal axis; and
wherein a bond exists between each of the flexure bond pads and the corresponding one of the plurality of FPC bond pads, and the bond is an ultrasonic gold bond or an anisotropic conductive film.
2. The disk drive of claim 1 wherein the widened region of each of the plurality of electrical traces defines a widened region width that is measured parallel to the flexure tail longitudinal axis, and that is in the range 150 microns to 200 microns.
3. The disk drive of claim 2 wherein the widened region of each of the plurality of electrical traces defines a widened region area that is at least 0.03 mm 2 .
4. The disk drive of claim 2 wherein the widened region of each of the plurality of electrical traces defines a widened region length that is measured transverse to the flexure tail longitudinal axis, and that is in the range 0.585 mm to 0.600 mm.
5. The disk drive of claim 1 wherein a thickness of the conductive layer is less than 15 microns, and the gold coating is a gold plating with a gold plating thickness of at least 1 microns, and a total thickness at each of the plurality of flexure bond pads is no more than 24 microns.
6. The disk drive of claim 5 wherein the structural layer and the dielectric layer are absent in the plurality of flexure bond pads, but where present in the flexure tail away from the plurality of flexure bond pads, a thickness of the structural layer is at least 15 microns, and a thickness of the dielectric layer is at least 5 microns.
7. The disk drive of claim 1 wherein each of the plurality of flexure bond pads is separated from another in a direction measured parallel to the flexure tail longitudinal axis, by an inter bond pad spacing of at least 0.3 mm but no more than 0.7 mm.
8. The disk drive of claim 1 wherein the bond is the anisotropic conductive film, and the anisotropic conductive film comprises an adhesive material that includes a plurality of electrically conductive beads of substantially similar size.
9. The disk drive of claim 8 wherein the plurality of electrically conductive beads is arranged in a monolayer with each of the plurality of electrically conductive beads in electrical contact with one of the plurality of flexure bond pads and the corresponding one of the plurality of FPC bond pads.
10. The disk drive of claim 1 wherein each of the widened regions of the plurality of electrical traces in the conductive layer has two opposing sides, and wherein the gold coating covers both of the two opposing sides.
11. The disk drive of claim 1 wherein the structural layer comprises stainless steel, the dielectric layer comprises polyimide, and the conductive layer comprises copper.
12. A head gimbal assembly (HGA) for a disk drive, the HGA comprising:
a read head; and
a suspension assembly that comprises
a load beam, and
a laminate flexure that comprises a structural layer, a dielectric layer, and a conductive layer that includes a plurality of electrical traces, the laminate flexure including a tongue portion that connects to the read head and a flexure tail that extends away from the tongue portion, the flexure tail defining a flexure tail longitudinal axis;
wherein the flexure tail includes a plurality of flexure bond pads, each of the plurality of flexure bond pads consisting of
a widened region of a corresponding one of the plurality of electrical traces in the conductive layer, and
a gold coating upon the widened region
wherein the widened region of each of the plurality of electrical traces extends transverse to the flexure tail longitudinal axis at least 2.5 times more than it extends parallel to the flexure tail longitudinal axis.
13. The HGA of claim 12 wherein the widened region of each of the plurality of electrical traces defines a widened region width that is measured parallel to the flexure tail longitudinal axis, and that is in the range 150 microns to 200 microns.
14. The HGA of claim 13 wherein the widened region of each of the plurality of electrical traces defines a widened region area that is at least 0.03 mm 2 .
15. The HGA of claim 13 wherein the widened region of each of the plurality of electrical traces defines a widened region length that is measured transverse to the flexure tail longitudinal axis, and that is in the range 0.585 mm to 0.600 mm.
16. The HGA of claim 12 wherein a thickness of the conductive layer is less than 15 microns, the gold coating is a gold plating having a gold plating thickness of at least 1 micron, and a total thickness at each of the plurality of flexure bond pads is no more than 24 microns.
17. The HGA of claim 16 wherein the structural layer and the dielectric layer are absent in the plurality of flexure bond pads, but where present in the flexure tail away from the plurality of flexure bond pads, a thickness of the structural layer is at least 15 microns, and a thickness of the dielectric layer is at least 5 microns.
18. The HGA of claim 12 wherein each of the plurality of flexure bond pads is separated from another in a direction measured parallel to the flexure tail longitudinal axis, by an inter bond pad spacing of at least 0.3 mm but no more than 0.7 mm.
19. The HGA of claim 12 wherein each of the widened regions of the plurality of electrical traces in the conductive layer has two opposing sides, and wherein the gold coating covers at least both of the two opposing sides.